CyberSecBulletin
CVE-2022-39377NVD status: Modified

sysstat: Incorrect Calculation of Buffer Size

Published Updated By the CyberSecBulletin desk

CVE-2022-39377 is a high-severity incorrect calculation of buffer size vulnerability in sysstat, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected sysstat versions: >= 9.1.16, < 12.7.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.36% chance of exploitation within 30 days, higher than 72% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of sysstat you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
Sysstatsysstat>= 9.1.16, < 12.7.1Not stated
DebianDebian Linux10.0Not stated
Fedora ProjectFedora35; 36; 37Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.0HighCNA (github.com)
CVSS 3.17.8HighNVD

Official description

sysstat is a set of system performance tools for the Linux operating system. On 32 bit systems, in versions 9.1.16 and newer but prior to 12.7.1, allocate_structures contains a size_t overflow in sa_common.c. The allocate_structures function insufficiently checks bounds before arithmetic multiplication, allowing for an overflow in the size allocated for the buffer representing system activities. This issue may lead to Remote Code Execution (RCE). This issue has been patched in version 12.7.1.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Incorrect Calculation of Buffer Size

The product does not correctly calculate the size to be used when allocating a buffer.

How developers prevent this class of flaw

  • When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts & characters to &amp; for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input buffer.
  • Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, not-a-number calculations, and how the language handles numbers that are too large or too small for its underlying representation. Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
  • Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.

More Incorrect Calculation of Buffer Size vulnerabilities (CWE-131)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Incorrect Calculation of Buffer Size vulnerabilities

Spotted an error? Tell us.